staging: comedi: mite: document mite_alloc()/mite_detach()

staging: comedi: mite: document mite_alloc()/mite_detach()

These functions are basically the comedi_driver (*attach)/(*detach)
for this driver.

For aesthetics, rename mite_alloc() to mite_attach() and pass the
comedi_device pointer to it instead of the pci_dev pointer.

Move the functions to the end of the file. This is typically where
a comedi_drivers (*attach)/(*detach) are located.

Add some docbook comments for these exported functions.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>